12th Class Physics Magnetism Question Bank

done MCQ - Moving Charges and Magnetism Total Questions - 113

• question_answer1)
  The magnetic effect of electric current was first noticed by:
  A)
  Andre Ampere                done clear
  B)
  Hendrik Antoon Lorentz done clear
  C)
  Hans Christian Oersted done clear
  D)
  Michael Faraday done clear
  View Solution play_arrow

• question_answer2)
  The laws obeyed by electricity and magnetism were unified and formulated by:
  A)
  J.C. Bose                       done clear
  B)
  James Maxwell done clear
  C)
  G. Marconi                    done clear
  D)
  Hans Christian Oersted done clear
  View Solution play_arrow

• question_answer3)
  Radio waves were produced by.............. and ..............
  A)
  James Maxwell. J.C. Bose                            done clear
  B)
  Lorentz. G. Marconi   done clear
  C)
  E.O. Lawrence, M.S. Livingstone                     done clear
  D)
  J.C. Bose. G. Marconi done clear
  View Solution play_arrow

• question_answer4)

  When a magnetic compass needle is carried nearby to a straight wire carrying current, then:

  (I) the straight wire cause a noticeable deflection in the compass needle.

  (II) the alignment of the needle is tangential to an imaginary circle with straight wire as its centre and has a plane perpendicular to the wire.

  A)
  (I) is correct done clear
  B)
  (II) is correct done clear
  C)
  Both (I) and (II) are correct done clear
  D)
  Neither (I) nor (II) is correct. done clear
  View Solution play_arrow

• question_answer5)
                            A current or a field going into the plane of the paper is depicted by a/an...............                                
  A)
  cross                done clear
  B)
  dot                           done clear
  C)
  both a. and b.                done clear
  D)
  arrow done clear
  View Solution play_arrow

• question_answer6)
  A current carrying wire is held over a magnetic needle, such that electric current is passed through it from south to north direction. Then the north pole of the needle will be deflected towards:
  A)
  east                   done clear
  B)
  west     done clear
  C)
  north                             done clear
  D)
  south done clear
  View Solution play_arrow

• question_answer7)
  When a magnetic field is applied on a stationary electron, it:
  A)
  remains stationary done clear
  B)
  spins about its own axis done clear
  C)
  moves in the direction of the field done clear
  D)
  moves perpendicular to the direction of the field done clear
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• question_answer8)
  Which one of the following is not correct about Lorentz force?
  A)
  In presence of electric field \[\overrightarrow{E}(r)\] and magnetic field \[\overrightarrow{B}(r)\]the force on a moving electric charge is \[\overrightarrow{F}=q[\overrightarrow{E}(r)+\overrightarrow{v}\times \overrightarrow{B}(r)]\]. done clear
  B)
  The force, due to magnetic field on a negative charge is opposite to that on a positive charge. done clear
  C)
  The force due to magnetic field becomes zero if velocity and magnetic field are parallel or anti-parallel done clear
  D)
  For a static charge the magnetic force is maximum. done clear
  View Solution play_arrow

• question_answer9)
  The magnetic force \[\overrightarrow{F}\] on a current carrying conductor of length l in an external magnetic field \[\overrightarrow{B}\] is given by:
  A)
  \[\frac{l\times \overrightarrow{B}}{\overrightarrow{l}}\]                 done clear
  B)
  \[\frac{\overrightarrow{l}\times \overrightarrow{B}}{l}\] done clear
  C)
  \[l(\overrightarrow{l}\times \overrightarrow{B})\]                    done clear
  D)
  \[{{l}^{2}}\overrightarrow{l}\times \overrightarrow{B}\] done clear
  View Solution play_arrow

• question_answer10)
  An alpha particle is moving perpendicular to the uniform magnetic field of 0.5 T with the velocity\[3\times {{10}^{5}}\text{ }m{{s}^{-1}}\]. What is the work done by the particle?
  A)
  \[1.5\times {{10}^{5}}J\]                      done clear
  B)
  Infinity done clear
  C)
  3 J                    done clear
  D)
  Zero done clear
  View Solution play_arrow

• question_answer11)
  A 2.5 m long straight wire having mass of 500 g is suspended in mid air by a uniform horizontal magnetic field B. If a current of 4 A is passing through the wire then the magnitude of the field is (Take \[g=10m{{s}^{-1}}\]):
  A)
  0.5 T                             done clear
  B)
  0.6 T    done clear
  C)
  0.25 T                           done clear
  D)
  0.8 T done clear
  View Solution play_arrow

• question_answer12)
  A conductor of length 20 cm carries a current of 1 A is kept at an angle with the magnetic field of 4 T. Find the angle between the conductor and the magnetic field if it experiences a force of 0.4 N.
  A)
  \[0{}^\circ \]                             done clear
  B)
  \[30{}^\circ \] done clear
  C)
  \[60{}^\circ \]                           done clear
  D)
  \[90{}^\circ \] done clear
  View Solution play_arrow

• question_answer13)
  The magnetic force per unit length on a wire carrying a current of 10 A and making an angle of \[45{}^\circ \] with the direction of a uniform magnetic field of 0.20 T is:
  A)
  \[2\sqrt{2}N{{m}^{-1}}\]                      done clear
  B)
  \[\frac{2}{\sqrt{2}}N{{m}^{-1}}\] done clear
  C)
  \[\frac{\sqrt{2}}{2}N{{m}^{-1}}\]                    done clear
  D)
  \[4\sqrt{2}N{{m}^{-1}}\] done clear
  View Solution play_arrow

• question_answer14)
  Which one of the following is correct statement about magnetic forces?
  A)
  Magnetic forces always obey Newton's third law        done clear
  B)
  Magnetic forces do not obey Newton's third law         done clear
  C)
  For very high current, magnetic forces obey Newton's third law done clear
  D)
  Inside low magnetic field, magnetic forces obey Newton's third law                                             done clear
  View Solution play_arrow

• question_answer15)
    If the velocity of charged particle has both perpendicular and parallel components while moving through a magnetic field, what is the path followed by a charged particle?
  A)
  Circular  done clear
  B)
  Elliptical done clear
  C)
  Linear                           done clear
  D)
  Helical done clear
  View Solution play_arrow

• question_answer16)
  Two charged particles traverse identical helical paths in a completely opposite sense in a uniform magnetic field \[\overrightarrow{B}={{B}_{0}}\widehat{k}\]
  A)
  They have equal z-components of momenta. done clear
  B)
  They must have equal charges. done clear
  C)
  They necessarily represent a particle-antiparticle pair. done clear
  D)
  The charge to mass ratio satisfy:             \[{{\left( \frac{e}{m} \right)}_{1}}+{{\left( \frac{e}{m} \right)}_{2}}=0\] done clear
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• question_answer17)
  A charged particle is moving in a circle of radius R with constant speed v, under the influence of a uniform magnetic field. The time period of motion:
  A)
  depends on both R and v done clear
  B)
  depends on v and not on R done clear
  C)
  depends on R and not on v done clear
  D)
  is independent of both R and v done clear
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• question_answer18)
  A charged particle enters a magnetic field H with its initial velocity making an angle of \[45{}^\circ \] with H. The path of the particle will be:
  A)
  a straight line                  done clear
  B)
  a circle done clear
  C)
  an ellipse                       done clear
  D)
  a helix done clear
  View Solution play_arrow

• question_answer19)
  If a charged particle enters a magnetic field, then it will:
  A)
  always experience a force by the magnetic field done clear
  B)
  never experience any force done clear
  C)
  experience a force, if it is moving at right angles to the field done clear
  D)
  experience a force, if it is moving parallel to the field done clear
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• question_answer20)
  A charge q moving in a staight line is accelerated by a potential difference V. It enters a uniform magnetic field B, perpendicular to its path. Then the radius of the circular path in which it travels will be:
  A)
  \[\sqrt{\frac{2mV}{q{{B}^{2}}}}\]                   done clear
  B)
  \[\sqrt{\frac{mV}{q{{B}^{2}}}}\] done clear
  C)
  \[\sqrt{\frac{q{{B}^{2}}}{2mV}}\]                   done clear
  D)
  \[\sqrt{\frac{q{{B}^{2}}}{mV}}\] done clear
  View Solution play_arrow

• question_answer21)
  Two particles A and B with same charges and different masses (\[{{m}_{A}}\] and \[{{m}_{B}}\] respectively) are moving in a plane inside uniform magnetic field which is perpendicular to the plane. The speed of the particles are \[{{v}_{A}}\] and \[{{v}_{B}}\] respectively and the trajectories are as shown in figure. Then:
  A)
  \[{{m}_{A}}{{v}_{A}}<{{m}_{B}}{{v}_{B}}\]          done clear
  B)
  \[{{m}_{A}}{{v}_{A}}>{{m}_{B}}{{v}_{B}}\] done clear
  C)
  \[{{m}_{A}}<{{m}_{B}}\] and \[{{v}_{A}}<{{v}_{B}}\] done clear
  D)
  \[{{m}_{A}}={{m}_{B}}\] and \[{{v}_{A}}<{{v}_{B}}\] done clear
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• question_answer22)
  What uniform magnetic field applied perpendicular to a beam of electrons moving at\[1.3\times {{10}^{6}}\text{ }m{{s}^{-1}}\], is required to make the electrons travel in a circular are of radius 0.35 m?
  A)
  \[2.1\times {{10}^{-5}}G\]                    done clear
  B)
  \[6\times {{10}^{-5}}T\] done clear
  C)
  \[2.1\times {{10}^{-5}}T\]                    done clear
  D)
  \[6\times {{10}^{-5}}G\] done clear
  View Solution play_arrow

• question_answer23)
  A charged particle is moving on circular path with velocity v in a uniform magnetic field B, if the velocity of the charged particle is doubled and strength of magnetic field is halved, then radius becomes:
  A)
  8 times                          done clear
  B)
  4 times done clear
  C)
  2 times                          done clear
  D)
  16 times       done clear
  View Solution play_arrow

• question_answer24)
  A A deuteron of kinetic energy 50 keV is describing a circular orbit of radius 0.5 m in a plane perpendicular to the magnetic field \[\overrightarrow{B}\]. The kinetic energy of the proton that describes a circular orbit of same radius and inside same \[\overrightarrow{B}\] is:
  A)
  25 keV                          done clear
  B)
  50 keV done clear
  C)
  200 keV                         done clear
  D)
  100 keV        done clear
  View Solution play_arrow

• question_answer25)
  Two \[\alpha \]-particles have the ratio of their velocities as 3 : 2 on entering the magnetic field. If they move in different circular paths, then the ratio of the radii of their paths is:
  A)
  2 : 3                  done clear
  B)
  3 : 2    done clear
  C)
  9 : 4                              done clear
  D)
  4 : 9          done clear
  View Solution play_arrow

• question_answer26)
  An electron of energy 1800 eV describes a circular path in magnetic field of flux density 0.4 T. The radius of path is \[(q=1.6\times {{10}^{-19}}C,\,{{m}_{e}}=9.1\times {{10}^{-31}}kg)\]
  A)
  \[2.58\times {{10}^{-4}}m\]         done clear
  B)
  \[3.58\times {{10}^{-4}}m\] done clear
  C)
  \[2.58\times {{10}^{-3}}m\]                  done clear
  D)
  \[3.58\times {{10}^{-3}}m\] done clear
  View Solution play_arrow

• question_answer27)
              An electron having momentum \[2.4\times {{10}^{-23}}kg\text{ }m{{s}^{-1}}\] enters a region of uniform magnetic field of 0.15 T. The field vector makes an angle of \[30{}^\circ \] with the initial velocity vector of the electron. The radius of the helical path of the electron in the field shall be:
  A)
  2 mm                            done clear
  B)
  1 mm     done clear
  C)
  \[\frac{\sqrt{3}}{2}mm\]                        done clear
  D)
  0.5 mm done clear
  View Solution play_arrow

• question_answer28)
  A charged particle is released from a rest in a region, having steady and uniform electric and magnetic fields. If the two fields are parallel to each other, then the path of the particle will be:
  A)
  ellipse                            done clear
  B)
  circle    done clear
  C)
  helix                              done clear
  D)
  straight line done clear
  View Solution play_arrow

• question_answer29)
  A charged particle moves along a circle under the action of magnetic and electric fields, then this region of space may have:
  A)
  \[E=0,\,B=0\]                done clear
  B)
  \[E=0,\,B\ne 0\] done clear
  C)
  \[E\ne 0,\,B=0\]             done clear
  D)
  \[E\ne 0,\,B\ne 0\] done clear
  View Solution play_arrow

• question_answer30)
  A charged panicle with charge 'q’ enters a region of constant, uniform and mutually orthogonal fields E B, with velocity v perpendicular to both E and B. The particle comes out without any change in magnitude or direction of its velocity. Then:
  A)
  \[\overrightarrow{v}=\frac{\overrightarrow{E}\times \overrightarrow{B}}{{{E}^{2}}}\]                   done clear
  B)
  \[\overrightarrow{v}=\frac{\overrightarrow{E}\times \overrightarrow{B}}{{{B}^{2}}}\] done clear
  C)
  \[\overrightarrow{v}=\frac{\overrightarrow{E}\times \overrightarrow{E}}{{{E}^{2}}}\]                   done clear
  D)
  \[\overrightarrow{v}=\frac{\overrightarrow{B}\times \overrightarrow{E}}{{{B}^{2}}}\] done clear
  View Solution play_arrow

• question_answer31)
  Biot-Savart law indicates that the moving electrons (velocity \[\overrightarrow{v}\]) produce a magnetic field \[\overrightarrow{B}\] such that:    (NCERT EXEMPLAR)
  A)
  \[\overrightarrow{B}\bot \overrightarrow{v}\]                     done clear
  B)
  \[\overrightarrow{B}\parallel \overrightarrow{v}\] done clear
  C)
  it obeys inverse cube law.                             done clear
  D)
  it is along the line joining the electron and point of observation.                                               done clear
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• question_answer32)
  For the magnetic field to be maximum due to a small element of current carrying conductor at a point, the angle between the element and the line joining the element to the given point must be:
  A)
  \[0{}^\circ \]       done clear
  B)
  \[90{}^\circ \]     done clear
  C)
  \[180{}^\circ \]                         done clear
  D)
  \[45{}^\circ \]           done clear
  View Solution play_arrow

• question_answer33)
  An element of \[0.05\text{ }\widehat{i}\text{ }m\]is placed at the origin as shown in figure which carries a large current of 10A. The magnetic field at a distance of 1 m in perpendicular direction is:
  A)
  \[4.5\times {{10}^{-8}}T\]                    done clear
  B)
  \[5.5\times {{10}^{-8}}T\] done clear
  C)
  \[5.0\times {{10}^{-8}}T\]                    done clear
  D)
  \[7.5\times {{10}^{-8}}T\] done clear
  View Solution play_arrow

• question_answer34)
  The magnitude of the magnetic field of a long straight wire carrying a current of 1 A at a distance of 2 cm is:
  A)
  \[{{10}^{-5}}T\]                      done clear
  B)
  \[{{10}^{-7}}T\] done clear
  C)
  \[2\times {{10}^{-7}}T\]                       done clear
  D)
  \[2\times {{10}^{-5}}T\] done clear
  View Solution play_arrow

• question_answer35)
  A straight wire of diameter 1 mm carries a current of 1 A. It is replaced by another wire of diameter 2 mm, carrying same current. The strength of the magnetic field is:
  A)
  twice the former value done clear
  B)
  one half of the former value done clear
  C)
  same as the former value done clear
  D)
  one quarter of the former value done clear
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• question_answer36)
  A current loop in a magnetic field:
  A)
  experiences a torque whether the field is uniform or non-uniform in all orientations done clear
  B)
  can be in equilibrium in one orientation done clear
  C)
  can be equilibrium in two orientations, both the equilibrium states are unstable done clear
  D)
  can be in equilibrium in two orientations, one stable while the other is unstable. done clear
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• question_answer37)
  A circular coil of radius a carries an electric current. The magnetic field due the coil at a point on the axis of the coil located at a distance r from centre of the coil, such that r>>a varies:
  A)
  \[\frac{1}{r}\]                            done clear
  B)
  \[\frac{1}{{{r}^{2}}}\] done clear
  C)
  \[\frac{1}{{{r}^{3}}}\]                         done clear
  D)
  \[\frac{1}{{{r}^{3/2}}}\] done clear
  View Solution play_arrow

• question_answer38)
  A circular loop of radius 3 cm is having a current of 12.5 A. The magnitude of magnetic field at a distance of 4 cm on its axis is:
  A)
  \[5.65\times {{10}^{-5}}T\]                   done clear
  B)
  \[5.27\times {{10}^{-5}}T\] done clear
  C)
  \[6.54\times {{10}^{-5}}T\]                   done clear
  D)
  \[9.20\times {{10}^{-5}}T\] done clear
  View Solution play_arrow

• question_answer39)
  A straight wire carrying a current of 13 A is bent into a semi-circular arc of radius 2 cm as shown in figure. The magnetic field is \[1.5\times {{10}^{-4}}T\] at the centre of arc, then the magnetic field due to straight segment is:
  A)
  \[1.5\times {{10}^{-4}}T\]                    done clear
  B)
  \[2.5\times {{10}^{-4}}T\] done clear
  C)
  zero                               done clear
  D)
  \[3\times {{10}^{-4}}T\] done clear
  View Solution play_arrow

• question_answer40)
                                      A wire in the form of a circular loop, of one turn carrying a current, produces magnetic induction B at the centre. If the same wire is Looped into a coil of two turns and carries the same current, the new value of magnetic induction at the centre is:
  A)
  B                      done clear
  B)
  2B      done clear
  C)
  4B                                done clear
  D)
  8B            done clear
  View Solution play_arrow

• question_answer41)
  A long wire carries a steady current. It is bent into a circle of one turn and the magnetic field at the centre of the coil is B. It is then bent into a circular loop of smaller radius, having ‘n' turns. The magnetic field at the centre of the coil will be:
  A)
  \[nB\]                            done clear
  B)
  \[{{n}^{2}}B\] done clear
  C)
  \[2nB\]                          done clear
  D)
  \[2{{n}^{2}}B\] done clear
  View Solution play_arrow

• question_answer42)
  A circular coil of wire consisting of 100 turns each of radius 9 cm carries a current of 0.4 A. The magnitude of magnetic field at the centre of the coil is:
  A)
  \[2.4\times {{10}^{-4}}T\]                    done clear
  B)
  \[3.5\times {{10}^{-4}}T\] done clear
  C)
  \[2.79\times {{10}^{-4}}T\]                   done clear
  D)
  \[3\times {{10}^{-4}}T\] done clear
  View Solution play_arrow

• question_answer43)
  The magnitude of the magnetic field at the centre of the tightly wound 150 turn coil of radius 12 cm carrying a current of 2 A is:
  A)
  18 G                             done clear
  B)
  19.7 G done clear
  C)
  15.7 G                          done clear
  D)
  17.7G done clear
  View Solution play_arrow

• question_answer44)
  A tightly wound 90 turn coil of radius 15 cm has a magnetic field of \[4\times {{10}^{-4}}T\] at its centre. The current flowing through it is:
  A)
  1.06 A                           done clear
  B)
  2.44 A done clear
  C)
  3.44 A                           done clear
  D)
  4.44 A done clear
  View Solution play_arrow

• question_answer45)
  A circular current loop of magnetic moment M is in an arbitrary orientation in an external magnetic field \[\overrightarrow{B}\]. The work done to rotate the loop by \[30{}^\circ \] about an axis prependicular to its plane is:            [NCERT EXEMPLAR]
  A)
  \[MB\]                           done clear
  B)
  \[\sqrt{3}\frac{MB}{2}\] done clear
  C)
  \[\frac{MB}{2}\]                                    done clear
  D)
  zero done clear
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• question_answer46)
  A current carrying circular loop of radius R is placed in the X-Y plane with centre at the origin. Half of the loop with x > 0 is now bent so that it now lies in the Y-Z plane.     [NCERT EXEMPLAR]
  A)
  The magnitude of magnetic moment now diminishes. done clear
  B)
  The magnetic moment does not change. done clear
  C)
  The magnitude of \[\overrightarrow{B}\] at (0, 0. z). z >> R increases. done clear
  D)
  The magnitude of \[\overrightarrow{B}\] at (0, 0. z). z >> R is unchanged. done clear
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• question_answer47)
  Ampere's circuital law is given by:
  A)
  \[\oint{\overrightarrow{H}\cdot \overrightarrow{dl}}={{\mu }_{0}}{{l}_{enc}}\]    done clear
  B)
  \[\oint{\overrightarrow{B}\cdot \overrightarrow{dl}}={{\mu }_{0}}{{l}_{enc}}\] done clear
  C)
  \[\oint{\overrightarrow{B}\cdot \overrightarrow{dl}}={{\mu }_{0}}J\]        done clear
  D)
  \[\oint{\overrightarrow{H}\cdot \overrightarrow{dl}}={{\mu }_{0}}J\] done clear
  View Solution play_arrow

• question_answer48)
  The correct plot of the magnitude of magnetic field \[\overrightarrow{B}\] vs distance r from centre of the wire is, if the radius of wire is R:
  A)
          done clear
  B)
  done clear
  C)
         done clear
  D)
  done clear
  View Solution play_arrow

• question_answer49)
  A current l flows along the Length of an infinitely long, straight thin walled pipe. Then:
  A)
  the magnetic field is same at all points, inside the pipe but not zero done clear
  B)
  the magnetic field at any point inside the pipe is zero     done clear
  C)
  the magnetic field is zero only on the axis of the pipe      done clear
  D)
  the magnetic field is different at different points inside the pipe                                                      done clear
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• question_answer50)
  A long straight wire in the horizontal plane carries a current of 75 A in north to south direction, magnitude and direction of field B at a point 3 m east of the wire is:
  A)
  \[4\times {{10}^{-6}}T\], vertical up done clear
  B)
    \[5\times {{10}^{-6}}T\], vertical down        done clear
  C)
  \[5\times {{10}^{-6}}T\], vertical up done clear
  D)
    \[4\times {{10}^{-6}}T\], vertical down        done clear
  View Solution play_arrow

• question_answer51)
  An electric current passes through a long straight wire. At a distance of 4 cm from the wire, the magnetic field is B. The magnetic field at 12 cm from the wire would be:
  A)
  B/6                               done clear
  B)
  B/3 done clear
  C)
  B/4                               done clear
  D)
  B/2             done clear
  View Solution play_arrow

• question_answer52)
  Ampere circuital law is used to find the:
  A)
  direction of current done clear
  B)
  direction of magnetic field done clear
  C)
  direction of magnetic motion of conductor done clear
  D)
  magnitude of current done clear
  View Solution play_arrow

• question_answer53)
  A solid cylindrical wire of radius R carries a current l. The ratio of magnetic field at points which are located at R/2 and 2R distance away from the axis of the wire is:
  A)
  1 : 1     done clear
  B)
  1 : 2     done clear
  C)
  2 : 1                              done clear
  D)
  1 : 4 done clear
  View Solution play_arrow

• question_answer54)
  An electron is projected with uniform velocity along the axis of a current carrying Long solenoid. Which of the following is true?                                                                                                          [NCERT EXEMPIAR]
  A)
  The electron will be accelerated along the axis. done clear
  B)
  The electron path will be circular about the axis. done clear
  C)
  The electron will experience a force at 45° to the axis and hence execute a helical path. done clear
  D)
  The electron will continue to move with uniform velocity along the axis of the solenoid. done clear
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• question_answer55)
  A solenoid has 1000 turns per metre length. If a current of 5 A is flowing through it, then magnetic field inside the solenoid is:
  A)
  \[2\pi \times {{10}^{-3}}T\]                   done clear
  B)
  \[2\pi \times {{10}^{-5}}T\] done clear
  C)
  \[4\pi \times {{10}^{-3}}T\]                   done clear
  D)
  \[4\pi \times {{10}^{-5}}T\] done clear
  View Solution play_arrow

• question_answer56)
  A solenoid coil of 200 turns/m is carrying a current of 3 A. The length of the solenoid is 0.2 m and has a diameter of 1 cm. The magnitude of the magnetic field inside the solenoid is:
  A)
  \[12\pi \times {{10}^{-5}}T\]                 done clear
  B)
  \[24\pi \times {{10}^{-5}}T\] done clear
  C)
  \[12\pi \times {{10}^{-4}}T\]                 done clear
  D)
  \[48\pi \times {{10}^{-6}}T\] done clear
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• question_answer57)
  A solenoid of 1.5 m length and 4.0 m diameter possesses 10 turns/cm. A current of 5 A is flowing through it The magnetic induction of axis inside the solenoid is:
  A)
  \[2\pi \times {{10}^{-3}}T\]                   done clear
  B)
  \[2\pi \times {{10}^{-5}}T\] done clear
  C)
  \[2\pi \times {{10}^{-3}}G\]                  done clear
  D)
  \[2\pi \times {{10}^{-5}}G\] done clear
  View Solution play_arrow

• question_answer58)
  A solenoid of Length 0.6m has a radius of 2 cm and is made up of 600 turns. If it carries a current of 4 A, then the magnitude of the magnetic field inside the solenoid is:
  A)
  \[6.024\times {{10}^{-3}}T\]     done clear
  B)
  \[8.024\times {{10}^{-3}}T\] done clear
  C)
  \[5.024\times {{10}^{-3}}T\]     done clear
  D)
  \[7.024\times {{10}^{-3}}T\] done clear
  View Solution play_arrow

• question_answer59)
  A solenoid of Length 50 cm, having 100 turns carries a current of 2.5 A. The magnetic field at one end of the solenoid is:
  A)
  \[3.14\times {{10}^{-4}}T\]                   done clear
  B)
  \[6.28\times {{10}^{-4}}T\] done clear
  C)
  \[1.57\times {{10}^{-4}}T\]                   done clear
  D)
  \[9.42\times {{10}^{-4}}T\] done clear
  View Solution play_arrow

• question_answer60)
  In which form the field Lines inside the infinite solenoid are present?
  A)
  Perpendicular straight lines   done clear
  B)
      Circular lines done clear
  C)
  Ellipsoidal lines           done clear
  D)
  Parallel straight lines                                    done clear
  View Solution play_arrow

• question_answer61)
  The magnetic field generated along the axis of a solenoid is proportional to:
  A)
  its length.                    done clear
  B)
  square of current flowing in it.                          done clear
  C)
  number of turns per unit length. done clear
  D)
  reciprocal of its radius,                                 done clear
  View Solution play_arrow

• question_answer62)
                       A long solenoid has magnetic field strength of \[3.14\times {{10}^{-2}}T\] inside it when a current of 5A passes through it The number of turns in 1m Length of the solenoid is:        
  A)
  1000                 done clear
  B)
  3000   done clear
  C)
  10000                           done clear
  D)
  5000         done clear
  View Solution play_arrow

• question_answer63)
  The magnitude of magnetic induction for a current carrying toroid of uniform cross-section is:
  A)
  uniform over the whole cross-section done clear
  B)
  maximum at the centre of cross-section done clear
  C)
  maximum on the outer edge done clear
  D)
  maximum on the inner edge. done clear
  View Solution play_arrow

• question_answer64)
  Which one of the following statements is correct?
  A)
  The magnetic field in the open space inside the toroid is constant. done clear
  B)
  The magnetic field in the open space exterior to the toroid is constant. done clear
  C)
  The magnetic field inside the core of toroid is constant. done clear
  D)
  The magnetic field inside the core of toroid is zero. done clear
  View Solution play_arrow

• question_answer65)
  A toroid having 200 turns carries a current of 1A. The average radius of the toroid is 10 cm. The magnetic field at any point in the open space inside the toroid is:
  A)
  \[4\times {{10}^{-3}}T\]                       done clear
  B)
  zero done clear
  C)
  \[0.5\times {{10}^{-3}}T\]                    done clear
  D)
  \[3\times {{10}^{-3}}T\] done clear
  View Solution play_arrow

• question_answer66)
  The current in the windings on a toroid is 2.0 A. There are 400 turns and the mean circumferential Length is 40 cm. If the inside magnetic field is 1.0 T, the relative permeability is near to:
  A)
  100                   done clear
  B)
  200    done clear
  C)
  300                               done clear
  D)
  400 done clear
  View Solution play_arrow

• question_answer67)
  The two parallel conductors carry equal currents in the same direction. What is the nature of the force acting between them?
  A)
  Repulsive                       done clear
  B)
  Attractive done clear
  C)
  Can not predict        done clear
  D)
  No force done clear
  View Solution play_arrow

• question_answer68)
  Two thin. Long parallel wires, separated by a distance (d) carry a current of i A in the same direction. They will:
  A)
  attract each other with a force per unit length of \[{{\mu }_{0}}{{i}^{2}}/(2\pi d)\] done clear
  B)
  repel each other with a force per unit length of \[{{\mu }_{0}}{{i}^{2}}/(2\pi d)\] done clear
  C)
  attract each other with a force per unit length \[{{\mu }_{0}}{{i}^{2}}/(2\pi {{d}^{2}})\] done clear
  D)
  repel each other with a force of per unit length \[{{\mu }_{0}}{{i}^{2}}/(2\pi {{d}^{2}})\] done clear
  View Solution play_arrow

• question_answer69)
  If distance between two current carrying wires is doubled, then force between them is:
  A)
  halved                           done clear
  B)
  doubled done clear
  C)
  tripled                            done clear
  D)
  quadrupled done clear
  View Solution play_arrow

• question_answer70)
  Two parallel wires 2m apart carry currents of 2A and 5A respectively in same direction, the force per unit length acting between the two wires is:
  A)
  \[2\times {{10}^{-6}}N/m\]                   done clear
  B)
  \[3\times {{10}^{-6}}N/m\] done clear
  C)
  \[1\times {{10}^{-6}}N/m\]       done clear
  D)
  \[4\times {{10}^{-6}}N/m\] done clear
  View Solution play_arrow

• question_answer71)
  A conductor of length 2 m carrying current 2A is held parallel to an infinitely Long conductor carrying current of 12 A at a distance of 100 mm, the force on small conductor is:
  A)
  \[8.6\times {{10}^{-5}}N\]                    done clear
  B)
  \[6.6\times {{10}^{-5}}N\] done clear
  C)
  \[7.6\times {{10}^{-5}}N\]                    done clear
  D)
  \[9.6\times {{10}^{-5}}N\] done clear
  View Solution play_arrow

• question_answer72)
  Two wires are kept parallel and carry equal currents separated by 2 cm apart. They experience an attractive force of \[16\times {{10}^{-5}}\] newton per unit length, find the current flowing in the two wires.
  A)
  \[16\times {{10}^{-5}}A\]                     done clear
  B)
  \[16A\] done clear
  C)
  \[4A\]                            done clear
  D)
  \[1A\] done clear
  View Solution play_arrow

• question_answer73)
  Two long straight wires carrying the same current and separated by a distance r, exert force F per unit length on each other. If the current is decreased to l / 2 and separation between them is increased to 2r, then force will become:
  A)
  8 F                    done clear
  B)
  2 F      done clear
  C)
  F / 2                              done clear
  D)
  F / 8 done clear
  View Solution play_arrow

• question_answer74)
  A current carrying loop is placed in a non-uniform magnetic field. It will experience:
  A)
  a force of repulsion          done clear
  B)
  a force of attraction done clear
  C)
  a torque but no force       done clear
  D)
  a force and a torque           done clear
  View Solution play_arrow

• question_answer75)
  The magnetic moment of a current l carrying circular coil of radius r and number of turns N varies as:
  A)
  \[\frac{1}{{{r}^{2}}}\]                         done clear
  B)
  \[\frac{1}{r}\] done clear
  C)
  \[r\]                               done clear
  D)
  \[{{r}^{2}}\] done clear
  View Solution play_arrow

• question_answer76)
  A small circular flexible Loop of wire of radius r carries a current l. It is placed in a uniform magnetic field B. The tension in the loop will be doubled if:
  A)
  l is doubled                    done clear
  B)
  B is halved done clear
  C)
  r is doubled                    done clear
  D)
  both B and l are doubled done clear
  View Solution play_arrow

• question_answer77)
  A 200 turn closely wound circular coil of radius 15 cm carries a current of 4 A. The magnetic moment of this coil is:
  A)
  \[36.5\text{ }A{{m}^{2}}\]                   done clear
  B)
  \[56.5\text{ }A{{m}^{2}}\] done clear
  C)
  \[66.5\text{ }A{{m}^{2}}\]                   done clear
  D)
  \[108\text{ }A{{m}^{2}}\] done clear
  View Solution play_arrow

• question_answer78)
  The magnetic moment associated with a circular coil of 35 turns and radius 25 cm, if it carries a current of 11 A is:
  A)
  \[72.2\text{ }A\,{{m}^{2}}\]                 done clear
  B)
  \[70.5\text{ }A\,{{m}^{2}}\] done clear
  C)
  \[74.56\text{ }A\,{{m}^{2}}\]               done clear
  D)
  \[75.56\text{ }A\,{{m}^{2}}\] done clear
  View Solution play_arrow

• question_answer79)
  The correct statement about magnetic moment is:
  A)
  it is a vector quantity done clear
  B)
  its unit is \[A{{m}^{2}}\] done clear
  C)
  its dimensions are \[[{{M}^{0}}{{L}^{2}}{{T}^{0}}{{A}^{1}}]\] done clear
  D)
  All of the above done clear
  View Solution play_arrow

• question_answer80)
  A circular coil of one turn and area A carrying a current has a magnetic dipole moment M. The current through the coil is:
  A)
  \[MA\]                           done clear
  B)
  \[\frac{A}{M}\] done clear
  C)
  \[\frac{M}{A}\]                          done clear
  D)
  \[\frac{M}{{{A}^{2}}}\] done clear
  View Solution play_arrow

• question_answer81)
  Two wires of same length are shaped into a square and a circle if they carry same current, ratio of magnetic moment is:
  A)
  \[2:\pi \]                         done clear
  B)
  \[\pi :2\]     done clear
  C)
  \[\pi :4\]                         done clear
  D)
  \[4:\pi \] done clear
  View Solution play_arrow

• question_answer82)
  An electron having charge e moves in a circular orbit of radius r, with frequency v. The magnetic moment associated with the orbital motion of the electron is:
  A)
  \[\pi ve{{r}^{2}}\]                    done clear
  B)
  \[\pi v{{r}^{2}}/e\] done clear
  C)
  \[\pi v\frac{e}{v}\]                     done clear
  D)
  \[\pi e\frac{{{r}^{2}}}{v}\] done clear
  View Solution play_arrow

• question_answer83)
  A current carrying loop is placed in a uniform magnetic field. The torque acting on it does depend upon:
  A)
  area of loop                   done clear
  B)
  value of current          done clear
  C)
  magnetic field                 done clear
  D)
  All of these                   done clear
  View Solution play_arrow

• question_answer84)
  A current carrying Loop is free to turn in a uniform magnetic field. The loop will then come to quilibrium when its place is inclined at:
  A)
  \[90{}^\circ \] to the direction of field done clear
  B)
  \[0{}^\circ \] to the direction of field done clear
  C)
  \[45{}^\circ \]to the direction of field done clear
  D)
  \[135{}^\circ \] to the direction of field done clear
  View Solution play_arrow

• question_answer85)
  A rectangular coil of wire carrying a current is kept in a uniform magnetic field. The torque acting on the coil will be maximum when:
  A)
  the plane of the coil is perpendicular to the field          done clear
  B)
  the normal to the plane of the coil is parallel to the field done clear
  C)
  the normal to the plane of the coil is perpendicular to the  field                                                                done clear
  D)
  the plane of the coil is making an angle of \[45{}^\circ \] with the field                                                                 done clear
  View Solution play_arrow

• question_answer86)
    A rectangular loop carrying a current is placed in a uniform magnetic field B. The area enclosed by the loop is A. If there are n turns in the loop, the torque acting on the loop is given by:
  A)
  \[ni(\overrightarrow{A}\times \overrightarrow{B})\]             done clear
  B)
  \[ni(\overrightarrow{A}\cdot \overrightarrow{B})\] done clear
  C)
  \[\frac{i(\overrightarrow{A}\times \overrightarrow{B})}{n}\]                        done clear
  D)
  \[\frac{i(\overrightarrow{A}\cdot \overrightarrow{B})}{n}\] done clear
  View Solution play_arrow

• question_answer87)
  A circular coil of 70 turns and radius 5 cm carrying a current of 8 A is suspended vertically in a uniform horizontal magnetic field of magnitude 1.5 T. The field lines make an angle of \[30{}^\circ \] with the normal of the coil then the magnitude of the counter torque that must be applied to prevent the coil from turning is:
  A)
  \[33\,Nm\]                      done clear
  B)
  \[3.3\,Nm\] done clear
  C)
  \[3.3\times {{10}^{-2}}Nm\]     done clear
  D)
  \[3.3\times {{10}^{-4}}Nm\] done clear
  View Solution play_arrow

• question_answer88)
  A circular coil of 25 turns and radius 12 cm is placed in a uniform magnetic field of 0.5 T normal to the plane of the coil. If the current in the coil is 6 A then total torque acting on the coil is:
  A)
  zero                               done clear
  B)
  3.4 N m done clear
  C)
  3.8 N m                         done clear
  D)
  4.4 N m done clear
  View Solution play_arrow

• question_answer89)
  The final torque on a coil having magnetic moment \[25\text{ }A{{m}^{2}}\] in a 5 T uniform external magnetic field, if the coil rotates through an angle of \[60{}^\circ \] under the influence of the magnetic field is:
  A)
  216.5 Nm                      done clear
  B)
  108.25 Nm done clear
  C)
  102.5 N m                     done clear
  D)
  258.1 N m done clear
  View Solution play_arrow

• question_answer90)
  The magnitude of torque experienced by a square coil of side 12 cm which consists of 25 turns and carries a current 10 A suspended vertically and the normal to the plane of coil makes an angle of \[50{}^\circ \] with the direction of a uniform horizontal magnetic field of magnitude 0.9 T is:
  A)
  1.6 Nm                          done clear
  B)
  1.2 Nm                     done clear
  C)
  1.4Nm              done clear
  D)
  1.8 Mm                     done clear
  View Solution play_arrow

• question_answer91)
  The magnetic moment \[({{\mu }_{e}})\] is directly proportional to orbital angular momentum (l), connected by a constant called the..............
  A)
  Planck's constant            done clear
  B)
  nuclear susceptibility done clear
  C)
  Gyromagnetic ratio    done clear
  D)
  chemical shift done clear
  View Solution play_arrow

• question_answer92)
  The numerical value of Gyromagnetic ratio for an electron is given by:
  A)
  \[8.8\times {{10}^{-12}}C\,k{{g}^{-1}}\]         done clear
  B)
  \[8.8\times {{10}^{10}}C\,k{{g}^{-1}}\] done clear
  C)
  \[1.6\times {{10}^{-19}}C\,k{{g}^{-1}}\]         done clear
  D)
  \[6.67\times {{10}^{11}}C\,k{{g}^{-1}}\] done clear
  View Solution play_arrow

• question_answer93)
  What is the correct value of Bohr magneton?          
  A)
  \[8.99\times {{10}^{-24}}A\,{{m}^{2}}\]        done clear
  B)
  \[9.27\times {{10}^{-24}}A\,{{m}^{2}}\] done clear
  C)
  \[5.66\times {{10}^{-24}}A\,{{m}^{2}}\]        done clear
  D)
  \[9.27\times {{10}^{-28}}A\,{{m}^{2}}\] done clear
  View Solution play_arrow

• question_answer94)
  In a moving coil galvanometer the deflection \[(\phi )\] on the scale by a pointer attached to the spring is:
  A)
  \[\left( \frac{NA}{kB} \right)l\]                  done clear
  B)
  \[\left( \frac{N}{kAB} \right)l\] done clear
  C)
  \[\left( \frac{NAB}{k} \right)l\]                  done clear
  D)
  \[\left( \frac{NAB}{kl} \right)\] done clear
  View Solution play_arrow

• question_answer95)
  A galvanometer is said to be sensitive, if it gives a:
  A)
  small deflection for a small current done clear
  B)
  small deflection for a large current done clear
  C)
  large deflection for a large current done clear
  D)
  large deflection for a small current done clear
  View Solution play_arrow

• question_answer96)
  In a moving coil galvanometer, the magnetic pole pieces are made cylindrical and a soft iron core is placed at the centre of the coil, the purpose for doing so is:
  A)
  to make the magnetic field strong done clear
  B)
  to make the magnetic field strong and radial done clear
  C)
  to make the magnetic field uniform done clear
  D)
  to make the magnetic field strong and uniform done clear
  View Solution play_arrow

• question_answer97)
  A moving coil type of galvanometer is based upon the principle that:
  A)
  coil carrying current experiences a torque in magnetic field. done clear
  B)
  a coil carrying current produces a magnetic field done clear
  C)
  a coil carrying current experiences impulse in a magnetic field done clear
  D)
  a coil carrying current experiences a force in a magnetic field done clear
  View Solution play_arrow

• question_answer98)
  Which of the following expressions are applicable to the moving coil galvanometer?
  A)
  \[{{\overrightarrow{F}}_{m}}=q(\overrightarrow{V}\times \overrightarrow{B})\]      done clear
  B)
  \[B={{B}_{0}}\tan \theta \] done clear
  C)
  \[\overrightarrow{\tau }\,=\,\overrightarrow{M}\,\times \,\overrightarrow{B}\]                        done clear
  D)
  None of these done clear
  View Solution play_arrow

• question_answer99)
  The sensitivity of a galvanometer will increase if:
  A)
  radius of coil is increased done clear
  B)
  number of turns in coil is decreased done clear
  C)
  radius of coil is decreased done clear
  D)
  a strong field is used done clear
  View Solution play_arrow

• question_answer100)
  What is the shape of magnet in moving coil galvanometer to make the radial magnetic field?
  A)
  Concave                        done clear
  B)
  Horse shoe magnet done clear
  C)
  Convex                         done clear
  D)
  None of these done clear
  View Solution play_arrow

• question_answer101)
  A small cylindrical soft iron piece is kept in galvanometer so that:
  A)
  a radial uniform magnetic field is produced done clear
  B)
  a uniform magnetic field is produced done clear
  C)
  there is a steady deflection of the coil done clear
  D)
  All of the above done clear
  View Solution play_arrow

• question_answer102)
  Which of the following material is used in making the core of a moving coil galvanometer?
  A)
  Copper                          done clear
  B)
  Nickel done clear
  C)
  Iron                  done clear
  D)
  Both a. and b. done clear
  View Solution play_arrow

• question_answer103)
  Among the following which can not be used to increase the voltage sensitivity of the galvanometer?    
  A)
  By increasing the area of the coil                        done clear
  B)
  By increasing the magnetic field                        done clear
  C)
  By decreasing the couple per unit twist                  done clear
  D)
  By increasing the number of turns                    done clear
  View Solution play_arrow

• question_answer104)
  If the current sensitivity of a galvanometer is doubled, then its voltage sensitivity will be:
  A)
  doubled                         done clear
  B)
  halved   done clear
  C)
  unchanged                     done clear
  D)
  four times done clear
  View Solution play_arrow

• question_answer105)
                                         A moving coil galvanometer can be converted into an ammeter by:
  A)
  introducing a shunt resistance of large value in series. done clear
  B)
  introducing a shunt resistance of small value in parallel. done clear
  C)
  introducing a resistance of small value in series.        done clear
  D)
  introducing a resistance of large value in parallel     done clear
  View Solution play_arrow

• question_answer106)
  Current sensitivity of a moving coil galvanometer is 5 div/mA and its voltage sensitivity is 20 div/V. The resistance of the galvanometer is...................
  A)
  \[25\,\Omega \]                           done clear
  B)
  \[250\,\Omega \] done clear
  C)
  \[40\,\Omega \]               done clear
  D)
  \[500\,\Omega \] done clear
  View Solution play_arrow

• question_answer107)
              A galvanometer of resistane \[\text{70}\,\Omega \], is converted to an ammeter by a shunt resistance \[{{r}_{s}}=0.03\,\Omega \]. The value of its resistance will become:                              
  A)
  \[0.025\,\Omega \]                      done clear
  B)
  \[0.022\,\Omega \] done clear
  C)
  \[0.035\,\Omega \]                      done clear
  D)
  \[0.030\,\Omega \] done clear
  View Solution play_arrow

• question_answer108)
  If the galvanometer current is 10 mA, resistance of the galvanometer is \[40\,\Omega \], and shunt of \[2\,\Omega \] is connected to the galvanometer, the maximum current which can be measured by this ammeter is:                      
  A)
  0.21 A                           done clear
  B)
  2.1 A      done clear
  C)
  210 A                            done clear
  D)
  21 A            done clear
  View Solution play_arrow

• question_answer109)
  A galvanometer of resistance \[40\,\Omega \] gives a deflection of 5 divisions per mA. There are 50 divisions on the scale. The maximum current that can pass through it when a shunt resistance of \[2\,\Omega \]. is connected is:
  A)
  210 mA            done clear
  B)
  155 mA                 done clear
  C)
  420 mA             done clear
  D)
  75 mA                  done clear
  View Solution play_arrow

• question_answer110)
  In an ammeter, 10% of main current is passing through the galvanometer. If the resistance of the galvanometer is G, then the shunt resistance will be:
  A)
  9 G                               done clear
  B)
  G/9      done clear
  C)
  90 G                             done clear
  D)
  G/90 done clear
  View Solution play_arrow

• question_answer111)
  The conversion of a moving coil galvanometer into a voltmeter is done by:
  A)
  introducing a resistance of large value in series done clear
  B)
  introducing a resistance of small value in parallel done clear
  C)
  introducing a resistance of large value in parallel done clear
  D)
  introducing a resistance of ?mall value in series. done clear
  View Solution play_arrow

• question_answer112)
  A galvanometer of resistance \[10\text{ }\Omega \] gives full-scale deflection when I mA current passes through it. The resistance required to convert it into a voltmeter reading upto 2.5 V is:
  A)
  \[24.9\,\Omega \]                        done clear
  B)
  \[249\,\Omega \] done clear
  C)
  \[2490\,\Omega \]                       done clear
  D)
  \[24900\,\Omega \] done clear
  View Solution play_arrow

• question_answer113)
  A volmeter which can measure 2 V is constructed by using a galvanometer of resistance \[12\,\Omega \] and that produces maximum deflection for the current of 2 mA, then the resistance R is:
  A)
  \[888\,\Omega \]             done clear
  B)
  \[988\,\Omega \] done clear
  C)
  \[898\,\Omega \]             done clear
  D)
  \[999\,\Omega \] done clear
  View Solution play_arrow